1. Field of the Invention
The present invention relates to a pointing device of a computer. More specifically, the present invention discloses a pointing device for generating a displacement signal according to the displacement of the pointing device with respect to a geomagnetic field.
2. Description of the Prior Art
In modern computer systems, a graphical user interface (GUI) has become the main method of interaction for a computer, user. GUIs are typically user-friendly and have simple and intuitive designs. In cooperation with the GUI, a pointing device has become a necessary peripheral device of the modern computer system by allowing the user to both operate the movement of the on-screen cursor and execute commands. It is therefore an important research objective of the information industry to develop an ergonomic and user-friendly pointing device.
The typical and commonly used pointing device is a mouse. The prior art mouse comprises a rolling ball mechanism disposed at the bottom of the mouse. When the user moves the mouse across a plane, the roller ball is caused to roll. The displacement of the mouse is measured by sensing the rolling action of the roller ball. This displacement measurement is translated into a displacement of the cursor on the computer screen. In other words, the cursor on the computer screen makes a corresponding movement when the user moves the mouse. As a result, the user may operate the GUI of the computer system with the mouse.
The drawback of the prior art mouse is that the mechanical mechanism of the roller ball is vulnerable to particles (such as dust), which results in wear of the mechanical mechanism. Because of this, periodic cleaning and maintenance are necessary. In addition, the user must operate the prior art mouse directly on a flat surface so that the roller ball contacts the flat surface. Consequently, the user can feel tired and strained due to these repetitive plane-limited movements. Furthermore, there is the possibility of serious injury with continued use.
It is therefore a primary objective of the claimed invention to provide a pointing device to sense displacement with respect to the geomagnetic field to solve the above-mentioned problems.
According to the claimed invention, the pointing device comprises a housing, at least a button installed on the housing for generating a control signal when a user presses the button, and a sensing module installed inside the housing. The sensing module further comprises a first magnetism detector comprising a first sensing axis, a second magnetism detector comprising a second sensing axis, an amplifier and a decoder. The first magnetism detector generates a first sensing signal according to a relative change of the first sensing axis with respect to a geomagnetic field. The second magnetism detector generates a second sensing signal according to a relative change of the second sensing axis with respect to the geomagnetic field. The amplifier is connected to the first magnetism detector and the second magnetism detector for amplifying the first sensing signal and the second sensing signal. The decoder is connected to the amplifier for generating a two-dimensional displacement signal according to the amplified first sensing signal and the amplified second sensing signal. The first sensing axis is not parallel with the second sensing axis and forms a predetermined angle with the second sensing axis. The first magnetism detector and the second magnetism detector respectively sense changes of the first sensing axis and the second sensing axis with respect to the geomagnetic field when the user moves the pointing device such that the decoder generates the corresponding two-dimensional displacement signal accordingly.
It is an advantage of the claimed invention that the pointing device utilizes an entirely electronic means to measure the displacement of the pointing device. Furthermore, the pointing device references the geomagnetic field. Therefore, the user feels less tired or strained after extended use of the pointing device.
These and other objectives and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.